<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>水平线</title>
</head>
<body>
  <p>hr 标签定义水平线：</p>
  <hr/>
  <p>这是段落。</p>
  <hr/>
  <p>这是段落。</p>
  <hr/>
  <p>这是段落。</p>
</body>
</html>